Data communication between a base station and a mobile station is typically conducted in one-to-one communication, so-called unicast communication. On the other hand, there is multimedia broadcast/multicast service (MBMS) for transmitting the same data from a base station to multiple mobile stations simultaneously, which attracts attention due to support for broadcast message service and fast video streaming service.
In the MBMS, if the same MBMS data pieces are transmitted from multiple base stations, a mobile station can receive the MBMS data with a high quality by soft-combining the same MBMS data pieces from the multiple base stations (so-called MBSFN (MBMS with Single Frequency Network). In this case, the mobile station has to receive the MBMS data from the multiple base stations with a delay time period less than or equal to a cyclic prefix (CP), and a longer CP would be required in consideration of delay of the MBMS data from a far base station. For example, the CP for unicast communication corresponds to 69μ seconds in LTE (3.9 generation (3.9G)) while the CP corresponds to 16.67μ seconds in the MBMS. In this manner, if the unicast channel and the MBMS channel (shared data channel (SDCH)), which have different CP lengths, are frequency-multiplexed and transmitted, orthogonality between the respective channels cannot be ensured. For this reason, the unicast channel and the MBMS channel are time-multiplexed per subframe unit in the LTE.